The Case for Lumbar Discectomy

Marcel F. Dvorak, M.D., FRCSC
Head, Division of Spine
Department of Orthopaedics
University of British Columbia
Vancouver, BC

Twenty years ago, while I was a resident, patients with a disc protrusion and sciatica would be told that "based on the evidence" if they chose to have surgery, their symptoms would be about the same within a year or two as if they had simply toughed it out. Back then, an open surgical discectomy on the orthopaedic or neurosurgical services involved an incision that you could put your fist into, often a bilateral exposure, and varying degrees of curettage within the disc space. The evidence' that we quoted was the Weber 1983 study6, which has been widely interpreted as showing no substantial long-term benefit to surgery over conservative care.

Today we have tubes to operate through, microscopes are in common use, and more than half of our discectomy patients can be in and out of hospital on the same day, or after one overnight stay at most. We not only have the recent publication of the SPORT Study7;8, but there is a comprehensive meta-analysis by Hoffman4, the Maine Lumbar Spine Study (MLSS)1, a study from Stanford2 and even several studies from my own centre in Vancouver5. Surely after 25 years, millions of dollars in peer reviewed research funding, and outcome collection on thousands of patients, we don't really need to debate the clinical role of lumbar microdiscectomy do we?

But it seems as if we are still debating the role of what is arguably the most predictable and effective surgical intervention available to spine surgeons today. For example, the SPORT study conclusions state that the benefits of surgery "were small and not statistically significant"8. Editorials claim that the proper role of surgery for disc herniation is unclear and suggest that a sham surgical trial is the only ethical next step3.

We are told about selection bias, intent-to-treat analyses, confounding, and the fact that without blinding, every intervention is subject to the expectations of the patient that the intervention will be successful. Based on these recent discussions, and remaining acutely aware of how terribly biased surgeons are towards surgery, we remain in a paralyzed state of equipoise, not knowing if we should be operating or not for lumbar disc herniation.

But let's wait for a minute and take a look at some of the data buried in these studies. In the SPORT study on disc herniation, for those patients that actually were operated on, their "treatment effect" was a 15 point reduction in the Oswestry Disability Index when compared to non-surgical care; a highly significant finding8. In the companion observational part of the SPORT study, a 36 point improvement in the ODI was seen at three months and was sustained out to two years7. Similar results for surgery have been reported in the Maine study and by others1;2;4.

So here we have an intervention (discectomy) that when applied to a well defined population (patients with sciatica secondary to disc herniation) produces an improvement in symptoms that is over three times what would be considered a clinically significant change and in essence returns patients to near-normal' within 6-8 weeks and we continue to debate its role? If anything, these recent studies have confirmed that the complication rate is exceedingly low, in the single digits, making this one of the safest and most predictable interventions available. The fundamental reason for the debate is that in the North American health care system (particularly in the US), patients are educated and informed and surgeons value and respect the preference of the patient and thus performing a petrie-dish type randomized trial is impossible.

In the SPORT study, about 40% of each of the surgery and non-surgical groups refused to follow their randomly determined treatment. This polluted' the analysis of the surgical group so profoundly that the intent-to-treat analysis (in which the surgical arm contained 60% surgical and 40% non-surgical patients) was essentially meaningless.

We have an exceedingly effective treatment in surgical discectomy, which when applied to a group of patients with sciatica, will predictably get them closer to normal' and get them there faster than will non-surgical treatment. This improved outcome for surgery persists despite that fact that the surgically treated patients were more severely disabled at the outset.

It is my opinion that we, as a profession, have been too politically correct and have failed to offer our patients one of the most effective surgical interventions available. Respecting a patient's preference does not involve misrepresenting the potential benefits of surgical intervention. In fairness, there is another lesson to be learned from the recent studies which is that the patients who tended to choose surgery, and benefited the most from surgery, were those whose symptoms were gradually getting worse and not better. When I advise patients, therefore, I discuss with them the temporal profile of their symptoms and if their symptoms are not improving or tending to worsen, then surgical treatment is certainly a more reasonable option than non-surgical care.

References

  1. Atlas S.J., Keller R.B., Wu Y.A., Deyo R.A., and Singer D.E. Long-term outcomes of surgical and nonsurgical management of sciatica secondary to a lumbar disc herniation: 10 year results from the maine lumbar spine study. Spine. 2005;30:927-35.
  2. Carragee E.J., Han M.Y., Suen P.W., and Kim D. Clinical outcomes after lumbar discectomy for sciatica: the effects of fragment type and anular competence. J.Bone Joint Surg.Am. 2003;85-A:102-8.
  3. Flum D.R. Interpreting surgical trials with subjective outcomes: avoiding UnSPORTsmanlike conduct. JAMA. 2006;296:2483-5.
  4. Hoffman R.M., Wheeler K.J., and Deyo R.A. Surgery for herniated lumbar discs: a literature synthesis. J.Gen.Intern.Med. 1993;8:487-96.
  5. Thomas K.C., Fisher C.G., Boyd M., Bishop P., Wing P., and Dvorak M. Outcome evaluation of surgical and non-surgical management of lumbar disc protrusion causing radiculopathy. Spine. in press. 2007.
  6. Weber H. Lumbar disc herniation. A controlled, prospective study with ten years of observation. Spine. 1983;8:131-40.
  7. Weinstein J.N., Lurie J.D., Tosteson T.D. et al. Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT) observational cohort. JAMA. 2006;296:2451-9.
  8. Weinstein J.N., Tosteson T.D., Lurie J.D. et al. Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT): a randomized trial. JAMA. 2006;296:2441-50.

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